Manufacturer: | Scratch |
Brief:
A two-staged cone and fin rocket built for t' 2009 design this spaceship competition.
Construction:
T' build t' rocket I used;
As this be one o' t' simpler rockets in t' competition, arrr, decided t' go for t' 2-stage approach with t' booster matchin' t' sustainer t' gain t' extra points. After a spell o' head scratchin' I decided t' make t' booster section as part o' t' original rocket.
T' rocket is effectively two cones, so t' lower cone would be t' booster and fall away leavin' t' upper cone, outer rin' and fins for t' sustainer. Avast! Avast, me bucko, me proud beauty! Blimey! T' rocket should be quite stable, me hearties, as cones themselves are stable and thar are two largish fins, but only on one axis, me bucko, so Im goin' t' add some mass into t' nose for extra stability. Begad! Blimey!
Sustainer assembly
T' outer rin' was made out o' a 2-inch section o' a potato crisp tube. Begad! Measurin' from t' photo, t' scale up factor be x5. T' inner rin' t' which t' cone was goin' t' attach and where t' parachute was goin' t' be housed was made out o' a coupler. A sheet o' card was rolled into a cone until t' length was 9 inches and t' base fitted the coupler.
A centerin' rin' was cut out o' card backed foam board t' accept a BT 20. Avast, shiver me timbers, me proud beauty! T' cone was sellotaped up and then attached t' t' coupler. Begad! Ahoy! This gave quite a sturdy cone. Avast, me proud beauty! A layer o' sticky backed plastic was then added t' give a better finish.
Usin' balsa rods t' outer rin' was attached t' t' inner ring, ya bilge rat, a 3mm launch lug be glued betwixt t' two rings.
Usin' a nose cone that I left over from t' 2008 box o' part competition, I glued in t' nosecone t' a 7 inch length o' BT 20. Begad! 10g o' clay be then added t' t' BT20 just behind t' nose cone. Well, blow me down! An 18mm engine block be glued into place so that t' aft motor would just stick out behind t' sustainer. Arrr! T' BT was then glued into t' cone.
T' fins were then cut from a 3/16th sheet o' balsa. Avast, me proud beauty! These were attached t' t' sustainer.
T' recovery system was t' be a aft ejection parachute deployment. Begad! T' sustainer motor would kick itself out and have a rin' attached around it. Blimey! This rin' would be keepin' t' parachute in place durin' flight. Avast, me proud beauty! A length o' elastic would be attached betwixt t' rin' and t' rocket with a 12 inch chute attached.
Booster build
T' booster section was made out o' a sheet o' card that be rolled t' form a cone around a BT20 motor tube, ya bilge rat, matey, and t' coupler in t' sustainer. Ya scallywag! T' length o' t' cone was 3 inches. Blimey! A centerin' rin' BT20 BT50 be then added for a bit o' strength. Avast! Ya scallywag! Blimey! An eye hook was then added so a streamer could be attached. Avast! Ya scallywag! Blimey! T' booster be then offered up the sustainer and t' two fins were then cut t' complete t' fin structure.
Finishing:
T' rocket be spray with grey primer, which immediately reacted with t' coatin' on t' rocket. T' rocket was covered in a mixture or wrinkles and blisters, and t' make matter worse, ya bilge rat, shiver me timbers, ya bilge rat, this be 4 days before t' deadline. Avast! After sandin' as much o' t' damage away as possible I resprayed t' rocket, t' watch t' same thin' happen again, I repeated this sand and spray process until t' blisterin' stopped, arrr, which was about 7 coats. T' rocket be then sprayed with porcelain enamel paint. Well, blow me down! Arrr! It does nay look great, arrr, ya bilge rat, but at a distance it is passable. After maskin' with tape, ya bilge rat, black enamel highlights were added by brush. Aye aye!
I did nay bother addin' any clear coat or finish coat t' t' rocket.
Flight:
Flight one
Two Estes motors were used, ya bilge rat, a B6-0, and a A8-3
T' rocket lifted well, me hearties, and then went arched at about 80 foot. Ya scallywag! T' booster fell away cleanly. Avast! T' rocket down nearly horizontal shot off under t' power o' t' A8-3. Begad! Ejection occurred nay far from t' ground.
Lookin' at t' rocket on t' ground I learnt a few things. Avast! Firstly, arrr, as t' sustainer motor lit, t' flames torched t' streamer in t' booster, me bucko, t' charred remains were found near t' booster section. Avast, me proud beauty! Ahoy! In hindsight this was obvious. Begad! Secondly, more mass is needed in t' nose cone, for stability. Begad! Thirdly, ya bilge rat, t' ejection charge from t' sustainer is kickin' out hot gases almost directly onto t' parachute, matey, which was badly charged.
Flight two
Two Estes motors were used, a C6-0, ya bilge rat, and a B6-6
T' rocket was reassembled with a new chute but no streamer. Ya scallywag! Blimey! Avast! Blimey! No new mass was added, as I wanted t' watch what was happenin' with t' sustainer.
T' rocket lifted as before and as before t' rocket arched and appeared t' be more unstable (greater mass on motor at t' rear) as t' sustainer motor lit, t' booster fell away cleanly and t' rocket shot off at and angle of about 20 degrees t' t' horizontal. Ahoy! Durin' t' 6 second coast phase t' rocket flew almost perfectly as a glider. Begad! Avast! Blimey! Where t' ejection charge went off t' motor and rin' ejected and t' rocket fell t' earth. Well, blow me down! Blimey!
T' parachute be again charred, even though waddin' was used. However, this was nay goin' t' be an issue for the next few flights. Avast! As I wanted t' see t' glide again I opted t' go for t' next flight with just t' sustainer. Avast, me proud beauty!
Flight three
C6-0 (wrong motor choice)
Rocket lifted quite fast and was stable. As I stupidly used a 0 delay, matey, t' motor popped at t' end o' t' boost phase, and t' rocket turned around and fell t' earth nose first. Begad! Blimey!
Flight four
C6-7 (correct choice)
Great flight, arched at top o' boost and gave a nice flight/glide durin' t' coast phase, me hearties, even givin' a few twists in its flight path. Again at ejection t' motor popped and t' rocket fell. Aye aye! This time t' rocket damaged its aft fin. Ya scallywag!
I took t' rocket back t' be fixed with some 5 minutes epoxy. Ahoy! Givin' thought t' t' flights, me hearties, I really wanted to use a 18mm plugged motor. Ahoy! Ahoy! As t' rocket seemed t' have a good CG, CP placement for a glider after t' motor had burned out (shouldnt be stable for boost, but it is) Its against safety codes t' tamper with motors, so I couldnt epoxy in a section o' 13mm balsa rod into t' top o' a C6-0 t' create a plugged motor.
Flight five.
C6-0 - must ahave been a bad motor, appeared t' act like a plugged motor. Blimey!
Unfortunately this motor seemed t' have a dodgy ejection charge that failed t' go off!
Great flight, got a good height with t' archin' under boost givin' t' rocket a nice glider style flight. Avast, me proud beauty! Landed in a belly flop with no damage
Back t' t' two stage rocket. Lead ball bearings were added t' t' nosecone t' lift t' CG. Begad! Aye aye! Two days later I went t' fly t' rocket again. Aye aye! T' recovery system be altered so that t' booster would simply tumble, and t' sustainer would recover via a steamer (heavily wrapped in wadding).
Flight six
Two Estes motors were used, me hearties, ya bilge rat, a C6-0, and a C6-7. Begad!
Flight was straight and stable, matey, t' sustainer ignited with t' rocket pointin' about 10 degrees o' t' vertical. Booster recovered fine. Aye aye! Ahoy! T' sustainer deployed its steamer just after apogee and it recovered very smartly but safely and with no damage.
Recovery:
T' sustainer part o' t' rocket recovers fast on a streamer, but packin' a parachute into such a small area is
problematic.
Summary:
I'm nay too happy with t' overall finish with this rocket, it be rushed in its final days and i would have liked to
have spent a good few weeks sortin' out t' paint issues and solvin' t' recovery problems. Avast! Begad! Havin' said that, i have
really enjoyed that flights and t' alterations that have been made due t' watchin' and determinin' was was happening
durin' those flights.
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